CodeCrafters co-founder here.

You're right, we could present it as just the articles.

Our overview is publicly accessible and doesn't require a paywall. https://app.codecrafters.io/courses/bittorrent/overview

All the "content" is also available on our GitHub https://github.com/codecrafters-io/build-your-own-bittorrent

If you'd like us to run tests against your code, show you progress, community examples, hints, and so on, then you can do the interactive experience, which requires signing up.